1. Field of the Invention
This invention relates to an electronic toll collection system (an ETC system) for a toll road.
2. Description of the Related Art
In an ETC system for a toll road, when every ETC vehicle passes through a tollgate, an accounting machine in the tollgate and the ETC vehicle communicate with each other by wireless to automatically implement an accounting process. Accordingly, it is unnecessary for the ETC vehicle to pause at the tollgate to pay toll. The ETC vehicle means a vehicle designed for the ETC system.
The ETC system can not automatically implement an accounting process with respect to a non-ETC vehicle. The non-ETC vehicle means a vehicle not adapted to the ETC system. It is necessary for the tollgate in the ETC system to discriminate non-ETC vehicles from ETC vehicles, and to guide the non-ETC vehicles to a booth where toll can be manually paid. It is desirable to provide a high accuracy of discrimination of non-ETC vehicles from ETC vehicles.